A stationary 0.1 g fly encounters the windshield of a 1300 kg automobile traveling at 110 km/h.
(a) What is the change in momentum of the car due to the fly?
____kg 路 km/h opposite the car's motion
(b) What is the change of momentum of the fly due to the car?
____kg 路 km/h along the car's velocity
(c) Approximately how many flies does it take to reduce the car's speed by 1 km/h?
_____fliesPhysics (Momentum) Help?
mass of the fly = (10^-4)kg
vel of fly after v= 110km/h
mass of car= 1300 kg
vel of car = 110km/h
mom. of car = mv = 1300 kg x110km/h =143,000 kgkm/h
Virtually NO change in momentum of the car since the fly's mass is insignificant.
b)
mom of fly before =(10^-4)kg x 0 = 0 kgkm/h
mom of fly after = 1.1 x 10^-2 kgkm/hr
change in fly's mom = 1.1 x 10^-2 kgkm/hPhysics (Momentum) Help?
its easy just use conservation of momentum. mass times velocity is momentum. momentum is conserved all the time. momentum before the collision is equal to momentum after the colission. draw a line and choose a coordinate axis. put the car on one end and the fly on the other. choose the direction that the car moves as the positive x direction. anything moving in that direction gets a posivive number for velocity. before the collision only the car has momentum becasuse the fly's velocity is zero. calculate the cars momentum its mass times velocity. you dont have to convert speed to metric because the answer asks for units of km/hr. now deal with the aftermath of the collision. calculate momentum. momentum is mass times velocity. velocity is not known yet so just use the letter v. mass is now 1300kg plus a gram. the gram has to be put in kilograms by sliding the decimal point and then it can be added to the 1300 kg.
now you set the before and after equat to one another and solve for v to do part a. to finish part a yoiu subtract final momentum from the initial momentum. for the fly the initial momentum is zero. so its final minus zero.
